可以使用数字生成器、递归查询、xmltable。有很多选择。例如：

with t as (select weight, '1 to '||n list from frequency)
select weight, 1 from t, xmltable(list)

或

with r(weight, n) as (select weight, n from frequency union all
                      select weight, n-1 from r where n-1 > 0)
select weight, 1 from r order by weight

D小提琴

一种简单的方法是递归cte：

with recursive cte as (
      select weight, n
      from t
      union all 
      select weight, n - 1
      from t
      where n > 1
     )
select weight, 1 as n
from cte;

请注意，尽管递归cte是标准的一部分，但是语法中有一些变化，因此您的数据库可能有点不同。
编辑：
在旧版本的oracle中，您可以生成所需的数字，然后生成数据：

with n as (select level as n
           from (select max(n) as n from t) n
           connect by level <= n
          )
select t.weight, 1 as n
from t join
     n
     on n.n <= t.n;

新版本的oracle支持递归cte。